Telephone-exchange system.



A. E. LUNDELL.

TELEPHONE EXCHANGE SYSTEM. APPLICATiON his!) WWI-0,1915. 1,1 9,458.

Patent-ed July 4, 1916.

b M To l fig IF I W E? km E Eg is Q is wl'lnesses' lnvenlor:

ML 'A/hen Luan a/r line terminals, and due to its being" a slow to the connector, therefore,

ALBEN E LUNDELL, OF NEW YORK, N, 1..

1 WESTERN ELECTRIC 'CGMPANY,

TELEPHONE-EXCHAEGE SYSTEM,

Application filed May 10,1915. Serial No. 27,037.

To all whomit 'llUlj/ concern Be it known that I, Ami-1X EMANUEL Luxni-xLL, citizenot' the Ynited States, residing at Xew York, in the county of Bronx and State ot'New York, have invented certain new and useful Improvements in Telephone EX- and units digits of the wanted line.

A feature of the invention consists in a circu t arrangement wherein the slow relay above referred ,to is also used as the called supervisory relav atter having co-operated A l i 1n the setting ot the connector onthe wanted relay, it provides the delayed disconnectfeature. that is, it prevents the connection from heing destroved by an accidental momentary opening and closing of the line circuit by the called party. I i

Another feature of the invention consists 7 -in providing this relay with a ,second marginal winding adapted to be included in cir cuit with the ringing generatc'ir and the called line, and to operate upon the response of the called party and open the ringing circuit. the first mentioned winding of the relay at this time being connected to one ot the talking condiu-t'ors ot' the connecting circuit to give a signal or ringing tone to the calling party to inform him that the.called party is being signaled.

The invention will be more readily understood when described with reference tothc accom 'iairving drawing. For simplicity the connector circuit. only is shown, it being understood thata connection would ordinarily lead from the calling substation A through one or more finde s and group selectors, "and finally-tln-ough the connector shown, to the called substation B. Vl hen the calling line has been extended through the relay 10 Specification. ofLetters Patent.

ground.

Hductor 18, side. switch arm contact, conductor 20. left-hand armature tor 21, armature winding or relay 12,

first contact, conducs.

o e on,

LASSIGNOR, BY lvLESNE' ASIGNI/I'ENTS, TO

IENCORPORATED, A CORPORATION OI NEW YORK.

- Patented July thereat is energized over the followingcircuit: free pole of the battery, left winding ot relay 1( conductor 1, terminal 2,,selector brush 3, line eonductor'4, telephone set, ot

the calling substation A,'senderS thereat,

line conductor 5, selector brush 6, terminal 7, conductors 8,1), right windingof relay 10 t 'ThiS relay front contact closes a circuit for slow-acting Relay '11 then, at its left hand arnniture an i front Contact, extends the back contact of the stepping relay t0 the pri mary stepping magnet 15.

ries of impulses corresponding to the tens digit of the \fllllZGLlIlUlIlbQl. Eaclrtiine the armature of the relay 10 closes its back contact, the following circuit is-closed'for the primary magnet which steps the connector brushes 4-0, 35, (12 into operative relation 'to the group of terminals containing the want ed line: tree pole of battery, magnet 15, con- 19 and its first of slow "relay 11, conducand back contact of stepping relay 10 to ground, The relay 11 is slo\\'acting andismaintained energizedduriug the breaks in the line circuit-in sending this series of impulses. sure of the back contact of the stepping relay 10, due to the first interruption otthe line circuit in sending this series of impulses, the slow relay 12 was energized over the following circuit: tree pole of battery, lettconductor 22, side and front cont-act switch arm 23 .and its tor 24, left-hand non-inductive winding ot slow-relay 11, left-hand armature and front contact thereot, conductor .21, armature and back contact of stepping relaylf) to ground.

a, rein,

n ,The calling suh scriber nowoperates his that S to send a se' lpon the first cloat its armature aud- Therefore, when the stepping relay 10 is maintained energized at the 'end of the series of interiauitions corresponding to the tens digit of thcwanted"number this relay 12 is dei i-iergized. \Vhen relay 12' became encrgized. in attracting its right armature into the ' engagen'ient with contact spring a circuit I escapement. magnet. in the well"- known lay 12 is dei ncrgized atthe end ot'- the series I ground. Each. time the stepping re'laylO is,

1 mg to the units, digit of the wanted line. I Upon the first interruption of the line circu t, the armature of the stepping relay 10, in closing its back contact, again energizes the slow relay 12 as before but now over side 15 switch'arm 23 and its second contact. Side switch escapement magnet 13 is consequently energized over the following circuit: free pole of battery, magnet 13, conductor 27, spring 25, right armature of slow relay 12, side switch arm 26 and its second contact to deen'ergized, it sends an impulse to the 'secing'circuit: free po of battery, magnet 16, conductor 74, side switch arm 19 and its second contact, conductor 20, left armature and front contact of slow relay 11, conductor.21, I armature, and back contact of stepping relay 10 to ground. The magnet 16 consequently i wanted line. The slow relay 12 is denergized as before at-the end'of the series of circuit interruptions, due to the maintained energization of the stepping relay 10, whereupon the escapement magnet 13 releases the side switch into. position 3, in which ringing current is applied to the selected line, if idle. Side .swit'ch arm 58 in movinginto position 3 places a ground upon multiple test ter11'1inals59-inthe connectors to, render in position 4.. 1

In pos'itidn 3, the side-switch eseapement pole of the battery, magnet 13,

conductor 27,- spring 25,conductors 75, 28'

and 29, side switch arm 26,- and itsthird contact to ground. The. magnet 13, at its armature and front contact, connects the pulsatingpurrent generatdr'BO'to the called line to signal the wanted subs'criberq ,This circuit .is as follows: free oleofgenerator 30, lamp 31, arlnatureancl front contact of "conductor 32, arm .33 and its conductor 37, bell 43 and condenser 70,,con-

1 ductor 38, contact 3.9, brush 40,-conduc'tor -l 41, arm 42 anditsthird contact towinding of relay-12 to conductor 48 which ondaryvertical magnet 16 over the followsteps the connector into connection with the c0114!) in' one sidejof the'talking circuit,

the line busy,.this 'groundbeing maintained.

- ceiver hook ing into this position '3' over the following release the connector; {The releamagnet 13, right winding of slow-relay 12,;

third contact,

armature'and back' con conductor 34, connector brush 35, contact- 36,

B, but is -not of suflicient I is connected to talking conductor. 46. Thus, the "cal lingsubscriber.is given a characteristic signal, indicating to. him that the wanted party is being rung, since the ringing current passing through the right;hand 7o winding of relay 12 will nduce currents in the left-hand winding of said relay.

\Vhen. the called party removes his, receiver and thus shunts bell 43 and condenser 70, the ri ht-hand winding of relay12 receives su 'cient current to cause it to attract its armatures. The engagement of the right-hand armature with contact spring 25 opens the circuit previously traced 'for the side switch escapement magnet 13 to ground by way of the side switch arm 26,-where upon the side switch is ,released'into position 4, in which position arms 23 and 26 close the tact 36,v out over the called line and through the telephonic apparatus-thereat by way of the conductors 37, 38, contact 39, connector brush '40, conductor 41, arm 42 and its fourth contact, left hand winding of imped ance coil 45, conductor 47, side switch arm 26 and its fourth contact'to ground. While the'left winding'of the relay 12 is included with the right windingof-the retardation whereas theother side of the circuit-contains only the left winding of .th'e retardation coil, this rclay and retardation coil are so wound as not to" unbalance the talking cir-' cuit.

If the called party should depress his remomentarily after having .responded, the connection wouldnot be destroyed since the relay 12 is slow-acting and its left armature would;;not .close its back contact which controls 'thecircuit of release [magnet 14. nation of the conversatiomthe called party en, however, I at the termireplaces his receiver upon its switchhook, and "assuming the calling partyhas not yet replaced, his receiver, the v relay-12; after an interval allows its arm'atures;to.' :.fa ll' f circuit;

125 tery, release magnet; 14,- conductor .49, com

tacts154v and; 55-," conductor "56,

i v esistance -71,' armature and frontjcontact a ,relay 11 to "grounds-The release ma 'e'tfinenergizing', E restores th connector an de switch in the me.

its fourthcontact, con-v wellknown manner, and

applies tone irom a busy back apparatus 64 to indicate to a calling party that the called party has hung up his receiver. When the calling party hangs up his receiver the relay 10 is denergized, andits armature in retracting releases relay 11, which at its left armature and back contact closes ground to conductor 69 leading to the preceding switches to release the same, this circuit leading by way of spring of the connector now closed to its left or normal contact. This ground renders the connector selectable by another testing selector. The retraction of the right armature of relay 11 deenergizes magnet 14.

In case the line selected had been busy as a called line, ground would have been pres out on test terminal 59, due to the side switch arm 58 of the connector-connected therewith being in position 3 or a. In case the selected line had been busy as a calling line, ground would have been present on the test terminal 59. through a contact (not shown) of the finder or equivalent switch. In this event, when the circuit of the slow relay 12 is broken by the maintained attraction of the armature of relay 10, after the series of interruptions of the line circuit corresponding to the units digit of the wanted number has been sent, the following circult is closed to the connector release magnet lei". free pole of the battery, release magnet 14,, conductors d9, 50, 51, left armature and back contact of slow relay 12, conductor 52, side switch arm 53 and its second contact, conductors :28, 60, side switch arm 58 and its second contact, test conductor (31, test brush 62 to grounded test contact :39. The release magnet immediately restores the connector and side switch to normal, and locks itself up in a circuit controlled at the armature and front contact of slow right relay 11 over the'cireuit previously traced.

, At its lower armature release magnet 14 connects the busy back mechanism 6i to conductor 48 connected to conductor 46 to indicate to the calling party that the wanted line is busy hen the calling party restores his receiver, relay 10 becomes del ncrgizcd and releases relay 11. The right armature of relay 1 in falling back opens the circuit of release magnetli, -which disconnects the busy back mechanism.

In case the calling party abandons the call after havingpartially set the connector or before the called party answers, the conof the folbatlery, release 49, 50, (37, side switch nector is released by the closure lowing circuit: free pole of magnet 1i, conductors arm "((3 and its first, second or th d contact, conductor (8, spring 65 and its r or oilnormal contact, conductor (ill, in:

and back contact of rela l" right armature and oacl to groimd. The n normal contact when the connector release circuit for said connector which said switch transfers said leases the connector,

following circuit: free pole of battery,'magnet 1%, conductor 4E9, springs tor 56, elf-normal contact 57 to ground, and is deenergized by the opening-of this oilreaches its normal position.

\Vhat is claimed is:

1. In a telephone exchange system, the combination with telephone lines, means for interconnecting the same including connectors, a steering switch and a release circuit for each connector, a slow relay adapted to control the same, and means actuated upon the response of the called party for includiine.

2. in a telephone exchange system wherein a slow-acting relay is employed at the connector to control a steering switch to effect the changeover operation at the end of each series oi line circuit interruptions caused by the sender, the combination with the connector, the slow relay and the steering switch, said steering switch being adapt ed when operated upon the termination of the last series of circuit interruptions to include said slow relay in circuit with the called line, saidrelay being adapted to respond when the called party answers, and a controlled at a back contact of said slow relay.

3. In a telephone exchange system, the combination with a calling and a called line, 'elephonic apparatus and signal receiving ,ttuilUQS therein, means for interconnecting said lines including connector switches, a source of ringing current, of a double wound relay, and means for applying current from saidsource to the called line over a circuit including one winding of said relzy and the signal receiving device in said line. and for connecting the other winding in circuit with the calling line and the telephonic apparatus therein to give a ringing signal to the calling party, said relay being adapted to operate upon the response ot the called party to open the ringing circuit.

4. In a telephone exchange system, the combination with telephone lines, means for interconnecting the same including connec-.

tor switches, a ringing generator, switch for each ping relay, a circuit therefor, a senderlin said circuit for intermittently operating said steppinga-elay, a double wound slow-acting relay controlling said steering switch, one of the windings of said relay being connected to the back contact of said by said. steering switcln'whereby upon the cessation of the last series of circuit interruptions said slow relay causes said steering switch to advance to the next'position, in winding the calling line and the a steering into circuit with 54, 55, conducstepping relay' and locks up over the w ing said slow relay in circuit with the called of said connectors, a stepother Winding in circuit with said ringing generator and the called line, means actuated upon the response of the called party for operating said slow relay to advance said 5 steering switch to the next position, a retardation coil, said switch in said position transferring said first mentioned winding into circuit with said coil and the called line, and a release circuit for said connector controlled at a back contact of said slow 10 relay.

In Witness whereof, I hereunto subscribe my name'this 8th day of May A. D. 1915.

ALBEN E. LUNDELL. 

